Conventional ladder rung has to satisfy two requirements of enough support strength and large enough area of surface. So far there are two kind of ladder rungs, one of which is ladder rung of aluminum alloy, the other one of which is ladder rung of plastic. However, they both have shortages, for example because the ladder rung is made of aluminum alloy, the cost of it is too high; because the ladder rung is made of plastic, the plastic ladder rung is difficult to connected to legs of the ladder.